<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title></title>
</head>
<body>
	<select name="" id="sele" onchange="a()">
		<option value="">请选择网站</option>
		<option value="http://www.baidu.com">百度</option>
		<option value="http://www.taobao.com">淘宝</option>
		<option value="http://www.163.com">网易</option>
	</select>
</body>
<script type="text/javascript">
	function a() {
		var sg = document.getElementById('sele').value;
		location.href = sg;
	}
</script>
</html>